In printers and duplicators commonly in use today, a photoconductive insulating member is typically charged to a uniform potential and thereafter exposed to a light image of an original document to be reproduced. The exposure discharges the photoconductive insulating surface in exposed or background areas and creates an electrostatic latent image on the member which corresponds to the image areas contained within the original document. Subsequently, the electrostatic latent image on the photoconductive insulating surface is made visible by developing the image with toner. Most development systems employ a developer material which comprises both charged carrier particles and charged toner particles which triboelectrically adhere to the carrier particles. During development the toner particles are attracted from the carrier particles by the charge pattern of the image areas on the photoconductive insulating area to form a powder image on the photoconductive area. This image is subsequently transferred to a support surface such as copy paper to which it is permanently affixed. Following transfer of the toner image to a support surface, the photoconductive insulating member is cleaned of any residual toner that may remain thereon in preparation for the next imaging cycle.
One of the more conventional approaches to fixing the toner image is through the use of heat and pressure by passing the print substrate containing the unfused toner image through a nip created between a pair of opposed roller members, at least one of them being heated and normally referred to as the fuser roll, and the other being pressed against the fuser roll and normally referred to as the pressure roll. During this procedure, the temperature of the toner material is elevated to a temperature at which the toner material coalesces and becomes tacky. This heating causes the toner to flow to some extent into the fibers or pores of the substrate. Thereafter, as the toner material cools, solidification of the toner material causes it to become bonded to the substrate. Typical of such fusing devices are two roll systems wherein the fuser roll is coated with a material such as silicone rubber or other low surface energy elastomer. The silicone rubbers that can be used as the surface of the fuser roll include room temperature vulcanizable silicones referred to as RTV silicones, liquid injection moldable or extrudable silicone rubbers, and high temperature vulcanizable silicones referred to as HTV silicones.
During the fusing process, and despite the use of low surface energy materials for the fuser roll surface, there is a tendency for the copy substrate to remain tacked to the fuser roll after passing through the nip between the fuser roll and the pressure roll. When this happens, the tacked print copy substrate does not follow the normal substrate path but rather continues in an arcuate path around the fuser roll, eventually resulting in a paper jam which will require operator involvement to remove the jammed paper before any subsequent printing cycle can proceed. Such a jammed piece of paper can also lead to a damaged fuser roll, a condition that requires a trained service technician to replace the roll, which is an expensive procedure. As a result it has been common practice to use one or more techniques to ensure that the print substrate is stripped from the fuser roll downstream of the fuser nip. One of the common approaches has been the use of a stripper finger or a plurality of stripper fingers placed in contact with the fuser roll to strip the print substrate from the fuser roll. Normally, the shape of the fingers, and their location and orientation relative to the fuser roll, are very important to their function, especially in the case of flexible stripper fingers. Still, even with the use of stripper fingers, a copy substrate can become jammed in the fuser assembly and when this occurs, the stripper fingers must be moved away from the jammed paper in order for the area of the paper jam to be accessible to an operator for clearance.
In a current fuser assembly, stripper fingers are mounted on a rotatable stripper finger mounting bar which moves the stripper fingers away from the fuser roll when the fuser assembly top cover is opened. However, the degree of rotation of the mounting bar is limited and at the end of the full rotation of the mounting bar the stripper fingers are still exposed to operator manipulation and/or damage during the process of clearing the jammed paper from the paper path. Due to the easily deformable nature of some types of stripper fingers and the criticality of maintaining their design-intent shape and orientation, it is desirable to keep the stripper fingers out of the jam clearance path of the casual operator in order to minimize their potential damage during jam clearance.
The following disclosures may be relevant to various aspects of the present invention: